Wideband Circularly Polarized Cavity-Backed Aperture Antenna With a Parasitic Square Patch

A technique to design a wideband circularly polarized (CP) cavity-backed aperture antenna is presented in this letter. The proposed antenna consists of an aperture antenna, a low-profile backed cavity, and a parasitic patch. Bidirectional radiation of the aperture antenna is changed to unidirectional radiation using the low-profile backed cavity. The parasitic patch is adopted to provide a favorable axial-ratio (AR) bandwidth. The proposed antenna combines the attractive features such as wide impedance and AR bandwidths, compact size, high aperture efficiency, as well as easiness of design, manufacture, and integration. The antenna operates at 6-GHz band with the overall volume of 0.8 λ
₀
×0.8 λ
₀
×0.3 λ
₀
. Measured results show that the antenna achieves a -10-dB impedance bandwidth of more than 70% and a 3-dB AR bandwidth of 43.3% with a peak gain of 8.6 dBi.